<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="generator" content="Docutils 0.9: http://docutils.sourceforge.net/" />
<title>RepastCity - Model Structure</title>
<style type="text/css">

/*
:Author: David Goodger (goodger@python.org)
:Id: $Id: html4css1.css 7056 2011-06-17 10:50:48Z milde $
:Copyright: This stylesheet has been placed in the public domain.

Default cascading style sheet for the HTML output of Docutils.

See http://docutils.sf.net/docs/howto/html-stylesheets.html for how to
customize this style sheet.
*/

/* used to remove borders from tables and images */
.borderless, table.borderless td, table.borderless th {
  border: 0 }

table.borderless td, table.borderless th {
  /* Override padding for "table.docutils td" with "! important".
     The right padding separates the table cells. */
  padding: 0 0.5em 0 0 ! important }

.first {
  /* Override more specific margin styles with "! important". */
  margin-top: 0 ! important }

.last, .with-subtitle {
  margin-bottom: 0 ! important }

.hidden {
  display: none }

a.toc-backref {
  text-decoration: none ;
  color: black }

blockquote.epigraph {
  margin: 2em 5em ; }

dl.docutils dd {
  margin-bottom: 0.5em }

object[type="image/svg+xml"], object[type="application/x-shockwave-flash"] {
  overflow: hidden;
}

/* Uncomment (and remove this text!) to get bold-faced definition list terms
dl.docutils dt {
  font-weight: bold }
*/

div.abstract {
  margin: 2em 5em }

div.abstract p.topic-title {
  font-weight: bold ;
  text-align: center }

div.admonition, div.attention, div.caution, div.danger, div.error,
div.hint, div.important, div.note, div.tip, div.warning {
  margin: 2em ;
  border: medium outset ;
  padding: 1em }

div.admonition p.admonition-title, div.hint p.admonition-title,
div.important p.admonition-title, div.note p.admonition-title,
div.tip p.admonition-title {
  font-weight: bold ;
  font-family: sans-serif }

div.attention p.admonition-title, div.caution p.admonition-title,
div.danger p.admonition-title, div.error p.admonition-title,
div.warning p.admonition-title {
  color: red ;
  font-weight: bold ;
  font-family: sans-serif }

/* Uncomment (and remove this text!) to get reduced vertical space in
   compound paragraphs.
div.compound .compound-first, div.compound .compound-middle {
  margin-bottom: 0.5em }

div.compound .compound-last, div.compound .compound-middle {
  margin-top: 0.5em }
*/

div.dedication {
  margin: 2em 5em ;
  text-align: center ;
  font-style: italic }

div.dedication p.topic-title {
  font-weight: bold ;
  font-style: normal }

div.figure {
  margin-left: 2em ;
  margin-right: 2em }

div.footer, div.header {
  clear: both;
  font-size: smaller }

div.line-block {
  display: block ;
  margin-top: 1em ;
  margin-bottom: 1em }

div.line-block div.line-block {
  margin-top: 0 ;
  margin-bottom: 0 ;
  margin-left: 1.5em }

div.sidebar {
  margin: 0 0 0.5em 1em ;
  border: medium outset ;
  padding: 1em ;
  background-color: #ffffee ;
  width: 40% ;
  float: right ;
  clear: right }

div.sidebar p.rubric {
  font-family: sans-serif ;
  font-size: medium }

div.system-messages {
  margin: 5em }

div.system-messages h1 {
  color: red }

div.system-message {
  border: medium outset ;
  padding: 1em }

div.system-message p.system-message-title {
  color: red ;
  font-weight: bold }

div.topic {
  margin: 2em }

h1.section-subtitle, h2.section-subtitle, h3.section-subtitle,
h4.section-subtitle, h5.section-subtitle, h6.section-subtitle {
  margin-top: 0.4em }

h1.title {
  text-align: center }

h2.subtitle {
  text-align: center }

hr.docutils {
  width: 75% }

img.align-left, .figure.align-left, object.align-left {
  clear: left ;
  float: left ;
  margin-right: 1em }

img.align-right, .figure.align-right, object.align-right {
  clear: right ;
  float: right ;
  margin-left: 1em }

img.align-center, .figure.align-center, object.align-center {
  display: block;
  margin-left: auto;
  margin-right: auto;
}

.align-left {
  text-align: left }

.align-center {
  clear: both ;
  text-align: center }

.align-right {
  text-align: right }

/* reset inner alignment in figures */
div.align-right {
  text-align: inherit }

/* div.align-center * { */
/*   text-align: left } */

ol.simple, ul.simple {
  margin-bottom: 1em }

ol.arabic {
  list-style: decimal }

ol.loweralpha {
  list-style: lower-alpha }

ol.upperalpha {
  list-style: upper-alpha }

ol.lowerroman {
  list-style: lower-roman }

ol.upperroman {
  list-style: upper-roman }

p.attribution {
  text-align: right ;
  margin-left: 50% }

p.caption {
  font-style: italic }

p.credits {
  font-style: italic ;
  font-size: smaller }

p.label {
  white-space: nowrap }

p.rubric {
  font-weight: bold ;
  font-size: larger ;
  color: maroon ;
  text-align: center }

p.sidebar-title {
  font-family: sans-serif ;
  font-weight: bold ;
  font-size: larger }

p.sidebar-subtitle {
  font-family: sans-serif ;
  font-weight: bold }

p.topic-title {
  font-weight: bold }

pre.address {
  margin-bottom: 0 ;
  margin-top: 0 ;
  font: inherit }

pre.literal-block, pre.doctest-block, pre.math {
  margin-left: 2em ;
  margin-right: 2em }

span.classifier {
  font-family: sans-serif ;
  font-style: oblique }

span.classifier-delimiter {
  font-family: sans-serif ;
  font-weight: bold }

span.interpreted {
  font-family: sans-serif }

span.option {
  white-space: nowrap }

span.pre {
  white-space: pre }

span.problematic {
  color: red }

span.section-subtitle {
  /* font-size relative to parent (h1..h6 element) */
  font-size: 80% }

table.citation {
  border-left: solid 1px gray;
  margin-left: 1px }

table.docinfo {
  margin: 2em 4em }

table.docutils {
  margin-top: 0.5em ;
  margin-bottom: 0.5em }

table.footnote {
  border-left: solid 1px black;
  margin-left: 1px }

table.docutils td, table.docutils th,
table.docinfo td, table.docinfo th {
  padding-left: 0.5em ;
  padding-right: 0.5em ;
  vertical-align: top }

table.docutils th.field-name, table.docinfo th.docinfo-name {
  font-weight: bold ;
  text-align: left ;
  white-space: nowrap ;
  padding-left: 0 }

h1 tt.docutils, h2 tt.docutils, h3 tt.docutils,
h4 tt.docutils, h5 tt.docutils, h6 tt.docutils {
  font-size: 100% }

ul.auto-toc {
  list-style-type: none }

</style>
</head>
<body>
<div class="document" id="repastcity-model-structure">
<h1 class="title">RepastCity - Model Structure</h1>

<div class="section" id="contexts-and-projections">
<h1>Contexts and Projections</h1>
<p>In Repast Simphony models, agents are organised into collections called <strong>Contexts</strong>. A context is basically a bucket that can be used to hold agents. Contexts are arranged hierarchically and can contain sub-contexts. Agents who exist in a sub-context also exist in the parent context, but the reverse is not necessarily true. For example, in a <em>School</em> context there might be <em>Teacher</em> and <em>Student</em> sub-contexts (and even further <em>Class</em> sub-contexts).</p>
<p><strong>Projections</strong> are used to give the agents a space and can define their relationships. For example, 'GIS' projections gives each agent an (x, y) spatial location and 'Network' projections allow relationships between agents to be defined (e.g. a social network). Projections are created for specific contexts and will automatically contain every agent within the context (so if an agent is added to a context it is also added to any projections which have been created on that context).</p>
<p>The figure below illustrates the organisation of the RepastCity model. Each context has an associated GIS projection to store the spatial locations of the objects.</p>
<img alt="figures/contexts_projections.png" src="figures/contexts_projections.png" />
<p>The <em>JunctionContext</em> is at the central means of routing agents. A Junction object is defined as the point at which two roads cross (e.g. an intersection). Therefore the <em>JunctionGeogaraphy</em> GIS projection is used to hold all the road intersections, and <em>RoadNetwork</em> is a network projection that contains the links between different junctions. Hence agents use the network to work out how to move from one place to another along the road network.</p>
<p>A fuller description of the routing algorithm itself is available on the <a class="reference external" href="http://crimesim.blogspot.com/2008/05/using-repast-to-move-agents-along-road.html">crimesim blog</a>.</p>
</div>
<div class="section" id="source-code">
<h1>Source Code</h1>
<div class="section" id="packages">
<h2>Packages</h2>
<p>The source code is organised into the following packages:</p>
<ul class="simple">
<li><tt class="docutils literal">repastcity3.agent</tt> contains classes describe the agents.</li>
<li><tt class="docutils literal">repastcity3.environment</tt> contains classes that define and interact with the environment (including reading input data, defining environment objects and generating routes).</li>
<li><tt class="docutils literal">repastcity3.main</tt> contains classes control model execution, including model initialisation and method scheduling.</li>
<li><tt class="docutils literal">repastcity3.exceptions</tt> contains all model-specific exception classes.</li>
</ul>
</div>
<div class="section" id="important-classes">
<h2>Important Classes</h2>
<p>The following classes are the most important ones to be aware of in order to extend the functionality of the model.</p>
<div class="section" id="repastcity3-agent-defaultagent">
<h3><tt class="docutils literal">repastcity3.agent.DefaultAgent</tt></h3>
<p>This is a simple example of an agent that implements the <tt class="docutils literal">IAgent</tt> interface. The most important is <tt class="docutils literal">step()</tt> which is called by the Repast scheduler once per model iteration. Therefore the easiest way to change how the agents behave is to edit the code in the <tt class="docutils literal">step()</tt> method.</p>
</div>
<div class="section" id="repastcity3-main-contextmanager">
<h3><tt class="docutils literal">repastcity3.main.ContextManager</tt></h3>
<p>The <tt class="docutils literal">ContextManager</tt> class is used to initialise the model. It is responsible for reading the input GIS files, creating contexts/projections, generating agents and initialising the schedule. It also keeps references to all the model contexts and projections for convenience.</p>
</div>
<div class="section" id="repastcity3-environment-route">
<h3><tt class="docutils literal">repastcity3.environment.Route</tt></h3>
<p>The <tt class="docutils literal">Route</tt> class contains the code to generate a route from one place to another along the road network. It works by creating a list of coordinates that an agent must traverse to get to their destination. <tt class="docutils literal">Route</tt> is responsible for actually moving the agents - e.g. an agent calls <tt class="docutils literal">route.travel()</tt> to move. A fuller description of the routing algorithm itself is available on the <a class="reference external" href="http://crimesim.blogspot.com/2008/05/using-repast-to-move-agents-along-road.html">crimesim blog</a>.</p>
</div>
</div>
</div>
</div>
</body>
</html>
